The present invention relates to a resin which may be used in the production of photosensitive elements and which renders such photosensitive elements developable by aqueous developers.
Although there are many resins known which may be used in the production of photosensitive elements in general, the majority of them are severely limited by the need to develop the photosensitive elements with solutions containing substantial amounts of organic solvents. Such developing solutions are undesirable in that their effluent is toxic and environmentally harmful and the solvents are costly.
It is known to produce resins for photosensitive applications containing 5 to 40% polyvinyl acetal, 5 to 35% azide-aryl substituted polyvinyl acetal, 1 to 45% polyvinyl acetate and 1 to 60% polyvinyl alcohol groups, as shown in U.S. Pat. No. 4,413,091. It is also known to prepare interpolymers for the stabilization of formaldehyde solutions wherein the interpolymer is composed of vinyl acetate, vinyl acetal and vinyl alcohol, as shown in U.S. Pat. No. 4,085,079. Similar polymers are also disclosed in U.S. Pat. No. 2,179,051. Each of these resins, though, when used in photosensitive elements, must be developed with developers which contain organic solvents.
What is desired, therefore, is a resin which may be used to produce a photosensitive element which is developable with a solution which does not necessarily contain organic solvents and need only contain minor amounts of salts and surfactants. Such resin should allow the photosensitive element to develop in a dissolving fashion, thereby substantially eliminating the presence of particles which may be re-deposited onto the element surface and interfere with the operation of the element. Such resin should also allow the production of a photosensitive element having superior sensitivity, image resolution, run length, and post-exposure and post development image contrast, and which is compatible with commonly used printing plate and press processing solutions.